BACKGROUND OF THE DISCLOSURE
[0001] The present invention relates to drive systems for operating at least two hydraulically
operated devices, and more particularly, to such systems wherein the load on one of
the devices is a function of the rate of operation of the other device, or of the
vehicle itself.
[0002] The present invention could be advantageously utilized in a number of applications,
such as a street sweeper, on which one hydraulic motor drives a brush, which sweeps
debris onto a conveyor, and the conveyor is driven by the other hydraulic motor. However,
the present invention is especially advantageous when used in connection with an unloading
auger drive system of a grain combine, and will be described in connection therewith.
Unloading auger drive systems for grain combines are illustrated and described in
U.S. Patent Nos. 3,938,683; 3,938,684; and 4,037,745, all of which are incorporated
herein by reference. In a typical grain combine, the grain being harvested is collected
in a grain tank which must be periodically unloaded. The unloading auger drive system
for such combines typically includes a horizontal auger disposed at or near the bottom
of the grain tank which transports grain to the lower end of a vertical auger. The
function of the horizontal auger is to keep the vertical auger full of grain. The
upper end of the vertical auger is typically associated with an unloading auger, through
which the grain is fed into a storage compartment of a transport vehicle, such as
a truck.
[0003] In the typical, prior art, unloading auger drive system of the type illustrated in
the above-cited patents, the various augers are normally interconnected by, and driven
by, a fairly complex system of clutches, right angle gear boxes, sprockets, and chains.
In one commercially available grain combine, the auger drive system is activated by
a hydraulically operated cylinder, which applies tension to a belt drive arrangement
which, in turn, drives the augers.
[0004] Although such auger drive systems have been generally satisfactory in operation,
certain problems have persisted. For example, if all of the augers are full of grain,
the resulting load on the drive system is excessive, and can stall the drive system.
Another problem frequently encountered is damage to the grain when the auger is being
driven while the grain is compacted and has nowhere to go. Finally, in order to deal
with the problem of overloading of the auger drive system, some combine tanks have
been provided with a system of adjustable slats in the bottom of the tank or hopper,
which adds substantially to the cost and overall complexity of the combine.
[0005] Although it was indicated that operation of the prior art auger drive systems has
been generally satisfactory, it has been observed that unloading the top one-half
of the grain tank takes substantially less time than unloading the bottom one-half
of the tank.
SUMMARY OF THE INVENTION
[0006] Accordingly, it is an object of the present invention to provide an improved unloading
auger drive system which will overcome the above problems of the prior art drive systems.
[0007] It is a more specific object of the present invention to provide such an improved
drive system which will relieve the load on the drive system when starting with the
augers full, but which will also result in a more uniform rate of unloading.
[0008] It is another, and more general object of the present invention to provide an improved
drive system for operating at least two hydraulically operated devices, wherein the
load on one of the devices is a function of the rate of operation of the other device,
or of the vehicle itself, in which the overall rate of operation of the drive system
is nearly optimized.
[0009] The above and other objects of the invention are accomplished by the provision of
an improved drive system for driving a first work device and a second work device,
wherein the load on the first work device is a function of the rate of operation of
the second work device. The improved drive system is characterized by a first hydraulic
motor driving the first work device and having a fluid inlet port and a fluid outlet
port, and a second hydraulic motor driving the second work device and having a fluid
inlet port and a fluid outlet port. A source of pressurized fluid is in fluid communication
with the fluid inlet port of the first hydraulic motor. A control valve means is provided
and includes a fluid inlet in fluid communication with the fluid outlet port of the
first hydraulic motor, a first fluid outlet in fluid communication with a system reservoir,
and a second fluid outlet in fluid communication with the inlet port of the second
hydraulic motor. The control valve means includes a valve member biased, by fluid
pressure at the fluid inlet port of the first hydraulic motor, toward a first position
permitting fluid communication from the inlet of the control valve means to the first
fluid outlet. The control valve includes means operable to bias the valve member toward
a second position permitting fluid communication from the fluid inlet of the control
valve means to the second fluid outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side elevation of a grain combine embodying a grain tank unloading system of
the type with which the present invention may be utilized.
[0011] FIG. 2 is a hydraulic schematic of the drive system of the present invention.
[0012] FIG. 3 is a side elevation, similar to FIG. 1, of a vehicle including an alternative embodiment
of the drive system of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] Referring now to the drawings, which are not intended to limit the invention, FIG.
1 illustrates a self-propelled grain combine, which will be described only briefly
herein in view of the above incorporation of U.S. Patent No. 4,037,745. The combine
includes a harvesting unit, such as a corn head 11, which gathers and delivers the
grain to a grain processing unit 13. From the unit 13, the grain is delivered by means
of a clean grain conveyor 15 to a grain tank 17. Typically, the grain tank 17 is disposed
rearwardly (to the right in FIG. 1) of an operator's station 19.
[0014] The grain tank 17 includes a pair of floor sections 21 and 23 which converge downwardly
and direct grain to a transverse (horizontal) auger conveyor 25 which is operable
to deliver grain from the lower part of the tank 17 to an inlet portion 26 of an upright
(vertical) auger conveyor 27.
[0015] After the grain is conveyed upwards by the vertical auger conveyor 27, it passes
through a transition housing 29, and then flows into an unloading auger conveyor 31,
which conveys the grain, then discharges it through an opening 33 at the rearward
end of the conveyor 31.
[0016] Referring now primarily to FIG. 2, it should be noted that one important aspect of
the present invention is that the auger conveyors 25 and 27 are not driven mechanically
(i.e., by gear sets, sprockets and chains, etc.) as in the above-incorporated patents.
Instead, it is an essential feature of the invention that the auger conveyors 25 and
27 are driven hydraulically.
[0017] Accordingly, the horizontal auger conveyor 25 is driven by a hydraulic motor 35,
while the vertical auger conveyor 27 is driven by a hydraulic motor 37. Although not
an essential feature of the invention, it is preferable that the hydraulic motors
35 and 37 comprise low-speed, high-torque ("LSHT") motors. More specifically, the
LSHT motors 35 and 37 may comprise gerotor LSHT motors of the type sold commercially
by the assignee of the present invention. It should be noted that the unloading auger
conveyor 31 is preferably still driven by mechanical means (typically, off of the
auger conveyor 27), and the conveyor 31 is not illustrated or described herein as
part of the system of the present invention.
[0018] Preferably, both of the motors 35 and 37 are supplied with pressurized fluid from
a single fluid source, such as a pump 39. In a typical vehicle installation, the pump
39 would supply hydraulic power (pressurized fluid) to several vehicle functions,
although the invention is not so limited. In the subject embodiment, the pump 39 supplies
pressurized fluid to a vehicle steering system, generally designated 41, and to an
auger motor drive system, generally designated 43. The pump 39 supplies pressurized
fluid to the vehicle steering system 41 and to the auger motor drive system 43 through
a load sensing, priority flow control valve 45, of the type which is now well known
to those skilled in the art, and is illustrated and described in U.S. Patent No. 3,455,210,
assigned to the assignee of the present invention and incorporated herein by reference.
Various load sensing priority flow control systems are illustrated and described in
greater detail in U.S. Patent No. 4,043,419, also assigned to the assignee of the
present invention and incorporated herein by reference.
[0019] As is well known to those skilled in the art, it is the function of the priority
valve 45 to apportion flow of pressurized fluid between the vehicle steering system
41 and the auger motor drive system 43, giving "priority" to the vehicle steering
system 41 (which is therefore also referred to as the "priority load circuit"). The
vehicle steering system 41 includes a steering control unit ("SCU"), designated 47,
which receives pressurized fluid from the pump 39 by means of the priority valve 45,
through a conduit 49. In response to rotation of a steering wheel 51, the pressurized
fluid in the conduit 49 is directed to one side or the other (as determined by the
direction of rotation of the steering wheel 51) of a steering cylinder 53. The construction
and operation of the vehicle steering system 41 is well known to those skilled in
the art, is not an essential feature of the invention, and therefore will not be described
further herein.
[0020] Preferably, the auger motor drive system 43 includes a valve block, generally designated
55, which may comprise a port block, mounted on the port face of the hydraulic motor
37. Schematically, the valve block 55 includes an inlet 57 which is connected to the
auxiliary flow port of the priority valve 45 by means of a conduit 59 (and therefore,
the drive system 43 is also referred to as the "auxiliary load circuit"). The valve
block 55 also includes an outlet 61 which is connected by means of a conduit 63 to
a fluid inlet port 65 of the motor 37. A fluid outlet port 67 of the motor 37 is connected
to a second inlet 69 of the valve block 55, which also has a second outlet 71 connected
to a fluid inlet port 73 of the motor 35. Finally, the valve block 55 includes a tank
outlet 75, which is connected to a system tank or reservoir R.
[0021] Within the valve block 55, the inlet 57 and outlet 61 are interconnected by a passage
77 (shown schematically as a "conduit"). Similarly, there is a passage 79 leading
to the second outlet 71, and a passage 81 leading to the tank outlet 75. Disposed
within the valve block 55, and in parallel between the passages 77 and 81 is a two-position,
two-way solenoid-operated valve 83. The valve 83 is biased by a spring 85 to the normally-open
position shown in FIG. 2. In this position, substantially all pressurized fluid entering
the inlet 57 is merely communicated through the valve 83 to the passage 81, and then
out the tank outlet 75 to the system reservoir R, with no pressure available to operate
either of the motors 35 or 37.
[0022] The valve 83 also includes a solenoid operator 87. When it is desired to operate
the auger motor drive system 43, the vehicle operator energizes the solenoid operator
87, moving the valve 83 to a position blocking communication from the passage 77 to
the passage 81, and thus maintaining pressurized fluid in the passage 77 and at the
outlet 61.
[0023] Also disposed in the valve block 55 is a two-position, three-way pressure response
valve 89, including a valve member 90, which is biased by a spring 91 to the position
shown in FIG. 2. In opposition to the biasing force of the spring 91, the valve member
90 is biased by the fluid pressure in the passage 77, by means of a pressure signal
93. The valve 89 includes an inlet 95, a first outlet 97, connected to the passage
81, and a second outlet 99, connected to the passage 79. Those skilled in the art
of hydraulic controls will understand that the valve 89 will normally modulate about
a set point, as determined by the equivalent force of the spring 91.
Operation
[0024] As was described in the background of the disclosure, one of the problems with the
prior art auger drive systems occurs upon start up, when the vertical auger 27 is
full of grain. With the present invention, if the vertical auger 27 is full of grain
upon start up, the motor 37 experiences a relatively high "starting torque", resulting
in the build up of a relatively high pressure in the conduit 63 and the passage 77.
Such high pressure is communicated by the pressure signal 93, biasing the valve member
90, in opposition to the force of the spring 91, to a position permitting substantially
unrestricted communication from the inlet 95 to the first outlet 97. Thus, the motor
35 is "unloaded" (i.e., it receives no pressurized fluid) and substantially all available
hydraulic power is available to drive the motor 37 and the vertical auger 27.
[0025] Those skilled in the art will understand that, although the auger motor drive system
43 may be operated "on-the-fly" (i.e., while the vehicle is moving), the vehicle is
normally moving in a straight line while the auger system 43 is operating. Therefore,
little if any fluid is being utilized by the vehicle steering system 41, and substantially
the entire output of pressurized fluid from the pump 39 is available to the auger
drive system 43.
[0026] As the vertical auger 27 transports some of the grain contained therein to the unloading
auger conveyor 31, the volume of grain in the auger conveyor 27 decreases, and therefore,
the torque on the motor 37 decreases, because the torque required to drive the vertical
auger 27 is approximately proportional to the volume of grain in the auger. With the
present invention, the total load pressures of the motors 35 and 37 together remains
approximately constant, i.e., the sum of the product of the pressure drop across each
motor and the flow therethrough is constant. It should be noted that, typically, the
vertical auger is enclosed, such that the only grain in the auger 27 is that which
is transported to it by means of the horizontal auger 25.
[0027] Thus, as the amount of grain in the vertical auger 27 drops, the pressure at the
fluid inlet port 65 of the motor 37 also drops, as does the pressure signal 93. As
the pressure signal 93 drops, the spring 91 biases the valve member 90 toward the
position shown in FIG. 2, and the pressure response valve 89 begins to communicate
some of the fluid from the fluid outlet port 67 of the motor 37 to the second outlet
99, from where it flows to the second outlet 71, and then to the fluid inlet port
73 of the motor 35. Therefore, as the amount of grain in the vertical auger 27 drops,
the horizontal auger 25 begins to operate, and the arrangement is self-compensating
in that, the less grain there is in the vertical auger 27, the more fluid will be
directed to the motor 35, thus operating the motor 35 and horizontal auger 25 faster,
increasing the amount of grain being fed into the vertical auger 27. Conversely, as
the amount of grain in the vertical auger 27 again begins to increase, the pressure
signal 93 increases, again moving the valve member 90 downward in FIG. 2, reducing
the amount of fluid being directed to the motor 35, and therefore decreasing the amount
of grain being fed by the horizontal auger 25 to the vertical auger 27.
Alternative Embodiments
[0028] As was mentioned in the background of the disclosure, the system of the present invention
could be utilized in various other applications wherein the load on one work device
is a function of the rate of operation of a second work device, or of the vehicle
itself. One example of another application for the system of the invention that was
mentioned in the BACKGROUND OF THE DISCLOSURE is a street sweeper, which typically
includes a rotating brush which sweeps debris onto a conveyor, which then transports
the debris up to a debris receptacle.
[0029] In the system as shown in FIG. 2, if applied to a typical street sweeper, the motor
35 would drive the rotating brush, while the motor 37 would drive the debris conveyor.
If the amount of debris being transported by the conveyor begins to overload the motor
37, it is better, rather than permitting the vehicle engine to stall, to reduce the
amount of debris being transported to the conveyor. This may be accomplished in either
of two ways. First, the speed of movement of the sweeper itself may be reduced, or
second, the flow to the motor 35 may be reduced, thus reducing the speed of operation
of the rotating brush. If the first alternative is to be utilized, the flow from the
second outlet 99 of the pressure response valve 89 may be used directly to drive the
propel motor of the sweeper, or may be used to command displacement of a variable
pump of a pump and motor propel system for the sweeper. Thus, the drive system of
the present invention gives the conveyor priority over the brush, so that the brush
doesn't overload the conveyor, and cause stalling of the overall drive system and
the vehicle engine.
[0030] Referring now primarily to FIG. 3, there is illustrated a further alternative embodiment
of the present invention. FIG. 3 illustrates, generically, a vehicle including an
operator station 101, and a material container 103. Disposed within the bottom of
the material container 103 is a horizontal conveyor, generally designated 105, which
is driven by the hydraulic motor 35. In FIG. 3, the hydraulic motor 35 is shown only
schematically, and is shown driving the horizontal conveyor 105 by means of a drive
shaft 107.
[0031] At the rearward end of the material container 103 is a door 109, which is hinged
to move from a closed, perfectly vertical position (not shown) to the partially open
position shown in FIG. 3. Operably associated with the door 109 is a vertical conveyor
111, the function of which is to receive material from the horizontal conveyor 105
and transport the material out of the container 103, typically into some other transport
vehicle or another form of storage. In FIG. 3, the vertical conveyor 111 is driven
by the hydraulic motor 37, which is shown only schematically in FIG. 3 and is shown
driving the conveyor 111 by means of a drive shaft 113.
[0032] The operation of the drive system 43, as shown in FIG. 2, would be substantially
the same in conjunction with the embodiment of FIG. 3 as it was in conjunction with
the auger system of the FIG. 1 embodiment. In view of the angle of orientation of
the vertical conveyor 111 in FIG. 3, it should be understood that the use herein of
the term "vertical" is not limited to being perfectly vertical. Instead the term "vertical"
as used herein merely requires that the device to which reference is made involves
some vertical movement or elevation, such that the torque on the motor 37 will tend
to be approximately proportional to the amount of material being transported by the
vertical auger or vertical conveyor.
[0033] The invention has been described in great detail in the foregoing specification,
and it is believed that various alterations and modifications of the invention will
become apparent to those skilled in the art from a reading and understanding of the
specification. It is intended that all such alterations and modifications are included
in the invention, insofar as they come within the scope of the appended claims.
1. A drive system (43) for driving a first work device (27;111) and a second work device
(25;105), wherein the load on the first work device is a function of the rate of operation
of the second work device; said drive system (43) being characterized by:
(a) a first hydraulic motor (37) driving said first work device (27;111) and having
a fluid inlet port (65) and a fluid outlet port (67);
(b) a second hydraulic motor (35) driving said second work device (25;105) and having
a fluid inlet port (73);
(c) a source of pressurized fluid (39) in fluid communication with said fluid inlet
port (65) of said first hydraulic motor (37);
(d) control valve means (89) including a fluid inlet (95) in fluid communication with
said fluid outlet port (67) of said first hydraulic motor, a first fluid outlet (97)
in fluid communication with a system reservoir (R), and a second fluid outlet (99)
in fluid communication with said fluid inlet port (73) of said second hydraulic motor
(35);
(e) said control valve means (89) including a valve member (90) biased, by fluid pressure
(93) at said fluid inlet port (65) of said first hydraulic motor (37), toward a first
position permitting fluid communication from said fluid inlet (95) of said control
valve means to said first fluid outlet (97); and
(f) means (91) operable to bias said valve member (90) toward a second position (FIG.
2) permitting fluid communication from said fluid inlet (95) of said control valve
means (89) to said second fluid outlet (99).
2. A drive system (43) as claimed in claim 1 characterized by said valve member (90),
in said first position, substantially preventing fluid communication from said fluid
inlet (95) of said control valve means (89) to said second fluid outlet (99).
3. A drive system (43) as claimed in claim 1 characterized by said valve member (90),
in said second position (FIG. 2), substantially preventing fluid communication from
said fluid inlet (95) of said control valve means (89) to said first fluid outlet
(97).
4. A drive system (43) as claimed in claim 1 characterized by said first work device
(27;111) comprising a device adapted to move a quantity of material, said quantity
of material being variable as a function of time; and said rate of operation of said
second work device (25;105) determining the quantity of material available to be moved
by said first work device (27;111).
5. A drive system (43) as claimed in claim 4 characterized by said first work device
(27;) having an inlet portion (26), an outlet portion (29), and means operable to
move material from said inlet portion to said outlet portion; and said second work
device (25) being operable to move material to said inlet portion (26) of said first
work device (27).
6. A drive system (43) as claimed in claim 1 characterized by, in said first position
of said valve member (90), substantially all fluid flowing through said first hydraulic
motor (37) flows to said system reservoir (R).
7. A drive system (43) as claimed in claim 1 characterized by, in said second position
of said valve member (90), substantially all fluid flowing through said first hydraulic
motor (37) flows to said second hydraulic motor (35).
8. A conveying system (43) for conveying material from a container (17) adapted to contain
a quantity of said material; said conveying system (43) including a vertical auger
(27) and means for driving said vertical auger, and further including a horizontal
auger (25) and means for driving said horizontal auger; said vertical auger (27) including
an inlet portion (26) disposed toward a lower portion of said container (17), and
an outlet portion (29) disposed toward an upper portion of said container, said horizontal
auger (25) being disposed to move said material to said inlet portion of said vertical
auger; said conveying system (43) being characterized by:
(a) a first hydraulic motor (37) comprising said means for driving said vertical auger
(27);
(b) a second hydraulic motor (35) comprising said means for driving said horizontal
auger (25);
(c) a first source (39) of pressurized fluid for said first hydraulic motor (37),
and a second source (67) of pressurized fluid for said second hydraulic motor (35);
(d) fluid control means (89) operable to control fluid flow from said second source
(67) of pressurized fluid to said second hydraulic motor (35), whereby the rate of
flow of said material from said outlet portion of said vertical auger (27) may be
maintained substantially constant.
9. A drive system (43) as claimed in claim 8 characterized by the total load pressures
of said first (37) and second (35) hydraulic motors remains approximately constant.
10. A drive system (43) as claimed in claim 8 characterized by said first hydraulic motor
(37) having a fluid inlet port (65) and a fluid outlet port (67), said fluid outlet
port (67) of said first hydraulic motor (37) comprising said second source of pressurized
fluid for said second hydraulic motor (35).
11. A drive system (43) as claimed in claim 10 characterized by said fluid control means
comprises control valve means (89) disposed in series flow relationship between said
fluid outlet port (67) of said first hydraulic motor (37) and said second hydraulic
motor (35).
12. A drive system (43) as claimed in claim 8 characterized by said fluid control means
(89) being operable to control fluid flow to said second hydraulic motor (35) as a
function of the fluid pressure from said first source (39) of pressurized fluid, with
a decrease in the fluid pressure from said first source (39) resulting in an increase
in fluid flow to said second hydraulic motor (35).
13. A drive system (43) as claimed in claim 8 characterized by said fluid control means
(89) being operable to control fluid flow to said second hydraulic motor (35) as a
function of the fluid pressure from said first source (39) of pressurized fluid, with
an increase in the fluid pressure from said first source (39) resulting in a decrease
in fluid flow to said second hydraulic motor (35).
14. A drive system (43) for use on a vehicle for driving a first work device (27;111)
and a second work device (25;105), wherein the load on the first work device is a
function of the rate of operation of at least one of the vehicle and the second work
device; said drive system (43) being characterized by:
(a) a first hydraulic motor (37) driving said first work device (27;111) and having
a fluid inlet port (65) and a fluid outlet port (67);
(b) a source of pressurized fluid (39) in fluid communication with said fluid inlet
port (65) of said first hydraulic motor (37);
(c) control valve means (89) including a fluid inlet (95) in fluid communication with
said fluid outlet port (67) of said first hydraulic motor, a first fluid outlet (97)
in fluid communication with a system reservoir (R), and a second fluid outlet (99);
(d) said control valve means (89) including a valve member (90) biased, by fluid pressure
(93) at said fluid inlet port (65) of said first hydraulic motor (37), toward a first
position permitting fluid communication from said fluid inlet (95) of said control
valve means to said first fluid outlet (97);
(e) means (91) operable to bias said valve member (90) toward a second position (FIG.
2) permitting fluid communication from said fluid inlet (95) of said control valve
means (89) to said second fluid outlet (99); and
(f) said second fluid outlet (99) is in fluid communication with a means operable
to control said rate of operation of said one of the vehicle and the second work device.